Mechanical rectifier



Jan. 12, 1954 f:` KOPPELMANN 2,666,102

MECHANICAL RECTIFIEIR Filed April 13, 1950 (-54 9 ma# wf w E 92 40 I l F176. l v L 1 I Wzl/111111111111 Patented Jan. 12, 1954 MECHANICAL RECTIFIER Floris Koppelmann, Berlin-Reinickendorf, Germany,

ration of Germany assignor to Licentia Patent-Verwaltungs-G. m. b. H., Berlin,

Germany, a corpo- Application April 13, 1950, Serial No. 155,585

Claims priority, application Germany November 4, 1949 (Cl. G-30) 16 Claims.

The present invention relates to a Contact a1'- rangement for mechanical current converters.

lt is an object of the present invention to provide an arrangement, the parte of which can be easily adjusted to varying conditions.

A Contact arrangement for mechanical current converters according to the present invention comprises in combination a stationary contact member, a movable contact member, resilient means for urging the movable contact member Iagainst the stationary Contact member, means driven synchronously vwith the current to be converted for separating the Amovable Contact member from the stationary Contact member, and. a movable bearing for the resilient means, the bearing moving synchronously with the contact separating means so that the stroke of the resilient means is constant during the opening of the contact members. Preferably a contact `arrangen'ient according to the present invention comprises a crank adapted to be driven synchronously with the current to be converted, a rod driven by the crank for separating the movable Contact member from the stationary contact member, the rod performing a small rotational movement in addition to the translate-ry motion for separating the Contact members, and a bearing `for the resilient means, the bearing moving synchronously with the rod so that the stroke o1^ the resilient means is constant during the opening or" the contact members.

Another embodiment comprises an eccentric adapted to be driven synchronously with the current to be converted, a rod having a recessed end engaging the eccentric, guide means for guiding the rod so that the end of the rod engaging the eccentric performs an oscillating motion, the rod being connected to the movable Contact member so as to separate the contact members during the stroke of the rod. Preferably a recess is yarranged at the other end of the rod, and a compression spring arranged in the recess and urging the movable contact member against the stationary contact member whereby the stroke of the compression spring is constant during the opening of the contact members.

A preferred embodiment of the present .invention comprises in combination a frame, two stationary contact members arranged in the frame, a movable contact .member arranged in the .frame and adapted to bridge in one end position thereof the stationart7 contact members, a shaft penetrating into the frame and adapted to be driven Isynchronously with the current to be converted, an leccentric arranged on vthe shaft, a pivoted Cil lever yengaging the eccentric, means for adjusting the pivot of the lever with respect -to the frame, a rod having one end thereof engaging the lever, the rod Vbeing guided in a substantially linear direction ina hole ofthe frame, a recess forming the .other end of the rod and accommodating the movable contact member so that it is separated from the stationarycontact members when the rod reaches substantially the one end position .thereof under the action of the eccentric ad the lever, and a compression spring arranged in the recess and urging the movable contact member against the stationary contact members, whereby the stroke of the compression spring is constant during the `openingof the Contact members.

Freferably a leaf spring connects the recess .for-ming the other end of the rod to the frame `and a compression spring is arranged between the other endV of the rod and the frame.

A preferred Iembed-im'ent of the present invention comprises in lcombination a frame having a substantiallyhorizontal wall and an upper and la lower chamber arranged, respectively, above and below the horizontal wall, two stationary contact Vmembers arranged in the upper chamber, a movable-contact member arranged in the upper charnber and adapted to bridge in one end position thereof the stationary contact members, a shaft lpenetrating into the lower chamber and driven 'synchronously with the current to be converted, an eccentric arranged on the shaft in the lower chamber, a -pivoted lever arranged in the lower `chamber and engaging the eccentric, a substantially vertical `pin arranged in an aperture of the horizontal wall and forming yat the lower end thereof the pivot Ioi the lever, means ior adjusting the pin with respect tothe aperture in the horizontal wall, asubstantially vertical Vrod having a lower end arranged in the lower chamber and engaging the lever, the rod being guided in a substantially vertical direction in a hole of the horizontal Wall, a recess forming the upper end of the rod `in the vupper chamber and accommodating the 'movable Contact member so that it is lifted from the stationary contact bers when the rod reaches substantially the upper lend position under the action of the eccentric and the lever, Vand a compression spring arranged in the recess and urging the movable contact member against the stationary contact members, whereby the stroke of the compression spring is constant during the opening of the contact members. In a lpreferred. embodiment a second shaft is adapted for angular adjustment and an arm rigidly secured to said second sha-it is connected to the pin so as to adjust it with respect to the horizontal wall, and screw means are connected to the pin and adapted to adjust the pin with respect to the horizontal wall.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specinc embodiments when read in connection with the accompanying drawings in which:

Fig. 1 shows a contact arrangement according to the invention.

Figs. 2 and 3 show two embodiments of contact arrangement according to the invention; and

Fig. e shows a practical embodiment of a contact arrangement.

In Fig. l movable contact bridge 4t bridges in its lowermost position stationary contacts 30 and Sta. The bridge it is moved upwards by the insulating head Eli of a rod 641 the other end of which is acted upon by an eccentric BB secured to a shaft i@ which is drivensynchronously with the alternating current to be rectified. The rod S carries at its lower end a plate iti abutting against the eccentric Gt. A guide member 'it guides the rod iii in a straight line vertical motion and a helical spring i8 arranged between the end plate and the guide member 'it keeps the plate afi in engagement with the eccentric et. The eccentric t6 is so shaped that the bridge iii makes contact with the contacts 3S and 30a for a period equivalent to 66 of the cycle of the alternating current and is out of contact for 123 during each half cycle of the current. A stationary member 8G is arranged above the bridge di? and a helical spring 82 is arranged between the bridge i6 and the stationary member S, the spring 82 supplying the contact pressure of the bridge fit. Spring 32 has a stroke which is the larger the smaller the time period is during which the bridge SG makes contact with the stationary contact members B and 33a. Thus the alternating strain on spring 82 is the higher the larger the distance is by which the bridge 40 is separated from the stationary contacts 30 and 30a. Since in a six-phase connection the contact time is only half as long as in a three-phase connection, namely theoretically 6 instead of 120, the stroke of spring 82 will be approximately twice as large in the six-phase connection as in the three-phase connection, which leads to diii'- culties in practical design.

The invention overcomes these diii'iculties by making the member against which the spring 82 abuts movable together with the rod ili. An embodiment of such a device is shown in Fig. 2 which diifers from the embodiment shown in Fig. 1 by the shape of the upper part of rod 64. n Fig. 2 the stationary contacts 30 and 30a are shown displaced through 90 against the position in which they are shown in Fig. 1, and are situated laterally of the head 8f3 of the rod fit. The head is preferably made of insulating material for instance a hard fabric and has a recess for the reception of the bridge 30 and the spring 82 abutting against the upper leg 8B of the head Sli which serves as a movable bearing for the spring 82. The other parts are similar to those shown in Fig. l.

1f the device is in the position shown in Fig. 2 in which the rod tf1 has its uppermost position and spring 'i3 is compressed, the bridge 4l! is lifted from contact pieces Se and Sila. Spring 82 is in its most expanded position and presses the bridge iii against the lower leg 9d of the head Eli. The lower leg E50 is in this position at a slightly higher level than the contact pieces 3B and 38a. so that it keeps the bridge iii out of contact with the latter. When the shaft it rotates and moves the eccentric toward the lowermost position, the rod Gli is moved correspondingly downward, spring it* keeping the end plate 'ifi in contact with the eccentric 55. During this movement the head Se is moved downward and at a certain moment, the bridge 4i@ comes into contact with stationary contacts 30 and Bda, the spring 82 preventing any rebound of the bridge di?. When the eccentric 55 moves further toward its lowermost position the spring 82 exerts a suicient pressure for pressing the bridge 4Q firmly against the ccntacts Sil and Bea. When the eccentric te passes its lowermcst position and moves on, the bridge is lifted once more from the stationary contacts 3d and 39a, the spring 82 keeping the bridge @iii in contact during the first part of the upward movement of rod iid. Thus the lifting and lowering of the bridge Ii is achieved smoothly and without any shock. The stroke of the spring S2 is independent of the movement of the rod Se since it is carried within the recess 86 of the head it of the rod @11.

The embodiment shown in Fig. 3 differs from that shown in Fig. 2 in some minor features among which is an improvement which allows to dispense with the guiding member le which in continuous operation needs lubricating with oil. in the design shown in Fig. 3 the lower end de of the rod 6ft is curved and engages the eccentric EEE. in consequence thereof the rod 64 carries out a small rotary movement in addition to its vertical movement because the lower end Q5 of the rod @A moves toward the left and the right by an amount corresponding to the eccentricity e of the eccentric. The upper leg 38 of the head ed is linked to a stationary part 92 by means of a leaf spring 9d so that if the rod 6d is suiciently long the bridge Lil] does not carry out any lateral movement. Practical tests have shown that the arrangement shown in Fig. 3 operates permanently even at a high contact pressure up to kg.

The operation of the device shown in Fig. 3 is essentially the same as that of the device shown in Fig. 2.

Referring now to Fig. 4 showing a practical embodiment of the contact arrangement according to Fig. 3 the shaft l@ carrying the eccentric 56 is driven by a synchronous motor and is arranged horizontally in a bottom recess iil of a frame m2. The bottom recess iii@ is filled with oil into which the lower side of the shaft i@ and the eccentric 66 dip. It is to be understood that the frame H32 accommodates twelve eccentrios which are keyed to a common shaft it.

The eccentric E56 is engaged by a roller l attached to one end of a lever t8 pivoted at li to a movable part w8 the position of which can be adjusted in the manner described hereinafter. The lever t8 carries a bearing il@ near its end carrying the roller iiili. The bearing ii@ is engaged by the tapered lower end [i2 of the rod S6 which is provided with an insulating head 84. The rod 815 passes through a boring il@ of the upper wall li of the frame 62 so that the head 8d is above the wall HS inside a casing H6 provided with a window i283 for the observation of the bridge i0 and the spring 82 and with a 5 rubber pack-ing v|212 for leading in the bus bars i2@ taking the part of the stationary contacts 3) and Stia. rihe ybus bars |24 are carried by insulating blocks 25. The casing |18 is preferably designed as a hood which can be removed from the top Wall |55 of the frame |02. The upper end of the insulating head 34 is connected by a leaf spring M to a stationary part 32 so that the head is restricted to movements essentially in the direction of the axis of the rod 64. must be understood, however, that the r'od 64 carries out very small lateral movement since the lever @t rotates about `the movable Apart w8 so that the bearing lli) carries out a motion along a circular arc about the pivot IB. A 'compression spring |28 is arranged rbetween the upper leg SS of the head 34 and a stationary part ISG and serves for pressing the lower end H2 of the rod iid against the bearing illl. The

spring t28 has a larger stroke than the spring 82 which, however, makes no difficulties-in practice since the spring |28 need not be a light spring. rPhe spring S2, however, should be as light as possible in order to avoid a rebounding when the bridge il@ engages the bus bars |24. i.

Thus the spring S2 should be made of high grade steel.

The roller iili can be replaced by a ball bearing or the like which may also be arranged on the shaft iii, the right end of lever 68 abutting against the cuter shell of the ball bearing.

operation of the device shown in Fig. 4 as far as it has been described is substantially the same as that of the device shown in Fig. 2 and need not be repeated.

In order to adjust the Contact time, i. e., the time during which the bridge 4e is in contact with the bus bars Hit, the pivot |66 of the lever El? is made adjustable by arranging the movable part Idil on the lower end of a vertical pin |32 passing through a sleeve |34 screwed into the upper wall HS of the frame |02. The pin |32 can be lifted or lowered by means of an adjusting screw 36, a lowering of the part |08 increasing the contact time and a lifting of 'part |98 decreasing the contact time. The screw |36 allows each pivot |96 to be adjusted individually. All the twelve pivots its can be adjusted simultaneously by the rotation of a shaft |38 to which twelve arms such as Idil are keyed. Each arm It carries with its outer end |42 a horizontal pin idd supporting a member |46 in which the vertical pin |32 is suspended. Thus it will be seen that by rotating the shaft |38 al1 pivots are adjusted simultaneously Whereas by the rotation of the screw |36 each pivot can be adjusted individually.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of arrangement for converting alternating current into direct current differing from the types described above.

While I have illustrated and described the invention as embodied in an arrangement for mechanically converting three-phase current into direct current, I do not intend to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of my invention.

Without further analysis, the foregoing will so fully reveal the gist of my invention that others can by applying current knowledge readily adapt it for various applications without `omitting features that, from the standpoint of prior art, fairly constitute essential characteristics ofthe generic or specific aspects of this 'invention and,

therefore, such adaptations should and are intended to 'be 'comprehended within the meaning and rangeof equivalence of the following claims.

What I claim 'as new and desire to secure by Letters Patent is:

1. A'contact arrangement for mechanical current converters, comprising in combination, a 'stationary contact member; a movable contact member; an eccentric adapted to be driven synchronously with the current to be converted; a pivoted lever engaging said eccentric; a rod engaging with one end thereof said lever; guide means for guiding said rod in a substantially linear direction; a recess arranged at the other end of said red; and a compression spring arranged in said recess and urging said movable contact member -against said stationary contact Amember whereby the stroke of said compression spring is constant during the opening of said contact members.

2. vA contact arrangement for mechanical current converters, comprising in combination, a stationary contact member; a movable contact member; an eccentric adapted to be driven synchronously with the current to be converted; a pivoted lever engaging said eccentric; means for radjusting the pivot of said lever; a rod engaging with one end thereof said lever; guide means for guiding said rod in a substantially linear direction; a recess arranged at the other end of said rod; and a compression spring arranged in said recess and urging said movable contact member against said stationary contact mea ber whereby the stroke of said compression spring is constant during the opening of said contact members.

3. A contact arrangement for mechanical current converters, comprising in combination, a frame; two stationary contact members arranged in lsaid frame; a movable contact member arranged in said frame and adapted to bridge in one end position thereof said stationary contact members; a shaft penetrating into said frame and adapted to be driven synchronously with the current to be converted; an eccentric arranged on said shaft; a pivoted lever engaging said eccentric; means for adjusting the pivot of said lever with respect to said frame; a rod having a Vone end thereof engaging said lever, said rod being guided in a sustantially linear direction in a hole of said frame; a recess forming the other end of said rod and accommodating said mov- -able contact member so that it is separated from said stationary contact members when said rod reaches substantially the one end position thereof under the action of said eccentric and said lever; and a compression spring arranged in said recess and urging said movable contact member against said stationary contact members, whereby the stroke of said compression spring is constant during the opening of said contact menibers.

4. A contact arrangement for mechanical current converters, comprising in combination, a

frame; two stationary contact members arranged Vin said frame; a movable contact member ar- 'ranged in said frame a-nd adapted to bridge in one end position thereof said stationary Contact members; a shaft penetrating into said frame and adapted to be driven synchronously with the current to be converted; an eccentric arranged on said shaft; a pivoted lever engaging said eccentric; means for adjusting the pivot of said lever with respect to said frame; a rod having a one end thereof engaging said lever, said rod being guided in a substantially linear direction in a hole of said frame; a recess forming the other end of said rod and accommodating said movable Contact member so that it is separated from said stationary contact members when said rod reaches substantially the one end position thereof under the action of said eccentric and said lever; a compression spring arranged in said Vrecess and urging said movable contact member current to be converted; an eccentric arranged on said shaft; a pivoted lever engaging said eccentric; means for adjusting the pivot of said lever with respect tosaid frame; a rod having a one end thereof engaging said lever, said rod being guided in a substantially linear direction in a hole of said frame; a recess forming the other end of said rod and accommodating said movable contact member so that it is separated from said stationary contact members when said rod reaches substantially the one end position thereof under the action of said eccentric and said lever; a compression spring arranged in said recess and urging said movable contact member against said stationary contact members, whereby the stroke of said compression spring is constant during the opening of said contact members; and a compression spring arranged between the other end of said rod and said frame.

6. A contact arrangement for mechanical current converters, comprising in combinationy a frame; two stationary contact members arranged in said frame; a movable contact member arranged in said frame and adapted to bridge in one end position thereof said stationary contact members; a shaft penetrating into said frame and adapted to be driven synchronously with the current to be converted; an eccentric arranged on said shaft; a pivoted lever engaging said eccentric; means for adjusting the pivot of said lever with respect to said frame; a rod having a one end thereof engaging said lever, said rod being guided in a substantially linear direction ina hole of said frame; a recess forming the other end of said rod and accommodating said movable contact member so that it is separated from said stationary contact members when said rod reaches substantially the one end position thereof under the action of said eccentric and said lever; a compression spring arranged in said recess and urging said movable contact member an upper and a lower chamber arranged, respectively, above and below said horizontal wall; two

Y stationary contact members arranged in lsaid upper chamber; a movable contact member arranged in said upper chamber and adapted to bridge in one end position thereof said stationary contact members; a shaft penetrating into said lower chamber and driven synchronously with the current to be converted; an eccentric arranged on said shaft in said lower chamber; a pivoted lever arranged in said lower chamber and engaging 4said eccentric; a substantially vertical pin arranged in an aperture of said horizontal wall and forming at the lower end thereof the pivot of said lever; means for adjusting said pin with respect to the aperture in said horizontal wall; a substantially vertical rod having a lower end arranged in said lower chamber and engaging said lever, said rod being guided in a substantially vertical direction in a hole of said horizontal wall; a recess forming the upper end of said rod in said upper chamber and accommodating said movable contact member so that it is lifted from said stationary contact members when said rod reaches substantially the upper end position under the action of said eccentric and lsaid lever; and a compression spring arranged in said recess and urging said movable contact member against said stationary contact members, whereby the stroke of said compression spring is constant during the opening of said contact members.

8. A contact arrangement for mechanical current converters, comprising in combination, a frame having a substantially horizontal wall and an upper and a lower chamber arranged, respectively, above and below said horizontal wall; two stationary contact members arranged in said upper chamber; a movable contact member arranged in said upper chamber and adapted to bridge in one end position thereof said stationary contact members; a shaft penetrating into said lower chamber and driven synchronously with the current to be converted; an eccentric arranged on said shaft in said lower chamber; a pivoted lever arranged in said lower chamber and engaging said eccentric; a substantially vertical pin arranged in an aperture of -said horizontal wall and forming at the lower end thereof the pivot of said lever; means for adjusting said pin with respect to the aperture in said horizontal wall; a substantially vertical rod having a lower end arranged in said lower chamber and engaging said lever, said rod being guided in a substantially vertical direction in a hole of said horizontal wall; a recess forming the upper end of said rod in said upper chamber and accommodating said movable contact member so that it is lifted from said stationary contact members when said rod reaches substantially the upf per end position under the action of said eccentric and said lever; a compression spring arranged in said recess and urging said movable contact member against said stationary contact members, whereby the stroke of said compression spring is constant during the opening of said contact members; and a leaf spring connecting said recess forming the upper end of said rod to said frame.

9. A contact arrangement for mechanical current converters, comprising in combination, a frame having a substantially horizontal wall and an upper and a lower chamber arranged, respectively, above and below said horizontal wall; two

lstationary contact members arranged in said upper chamber; a movable contact member ar- S ranged in said upper chamber and adapted to bridge in one end position thereof said stationary contact members; a shaft penetrating into saidv lower chamber and driven synchronously with the current to be converted; an eccentric arranged on said shaft in said lower chamber; a pivoted lever arranged in said lower chamber and engaging said eccentric; a substantially vertical pin arranged in an aperture of said horizontal wall and forming at the lower end thereof the pivot of said lever; means for adjusting said pin with respect to the aperture in said horizontal wall; a substantially vertical rod having a lower end arranged in said lower chamber and engaging said lever, said rod being guided in a substantially vertical direction in a hole of said horizontal wall; a recess forming the upper end of said rod in said upper chamber and accommodating said movable contact member so that it is lifted from said stationary contact members when said rod reaches substantially the upper end position under the action of said eccentric and said lever; a compression spring arranged in said recess and urging said movable contact member against said stationary contact members, whereby the stroke of said compression spring is constant during the opening of said contact members; and a compression spring arranged between the upper end of said rod and said frame.

10. A contact arrangement for mechanical current converters, comprising in combination, a frame having a substantially horizontal wall and an upper and a lower chamber arranged, respectively, above and below said horizontal Wall; two stationary contact members arranged in said upper chamber; a movable contact meniber arranged in said upper chamber and adapted to bridge in one end position thereof said stationary contact members; a shaft penetrating into said lower chamber and driven synchronously with the current to be converted; an eccentric arranged on said shaft in said lower chamber; a pivoted lever arranged in said lower chamber and engaging said eccentric; a substantially vertical pin arranged in an aperture of said horizontal wall and forming at the lower end thereof the pivot oi said lever; means for adjusting said pin with respect to the aperture in said horizontal wall; a substantially vertical rod having a lower end arranged in said lower chamber and engaging said lever, said rod being guided in a substantially vertical direction in a hole of said horizontal wall; a recess forming the upper end of said rod in said upper chamber and accommodating said movable contact member so that it is lifted from said stationary contact members when said rod reaches substantially the upper end position under the action of said eccentric and said lever; a compression spring arranged in said recess and urging said movable contact member against said stationary contact members, whereby the stroke of said compression spring is constant during the opening of said contact members; a leaf spring connecting said recess forming the upper end of said rod to said frame; and a compression spring arranged between the upper end of said rod and said frame.

1l. A contact arrangement for mechanical current converters, comprising in combination, a frame having a substantially horizontal wall and an upper and a lower chamber arranged, respectively, above and below said horizontal wall; two stationary contact members arranged in said upper chamber; a movable contact member arranged in said upper chamber and adapted to 'bridge in one end position thereof said stationary contact members; a first shaft penetrating into said lower chamber and driven synchronously with the current to be converted; an eccentric arranged on said first shaft in said lower chamber; a pivoted lever arranged in said lower chair.- ber and engaging said eccentric; a substantially vertical pin arranged in an aperture or said horiu zontal wall and forming at the lower end thereof the pivot of said lever; a second shait adapted for angular adjustment; an arm rigidly secure-i to said second shaft and connected to said pin so as to adjust it with respect to said horizontal wall; screw means connected to said pin and adapted to adjust said pin with respect to said horizontal wall; a substantially vertical rod having a lower end arranged in said lower chamber and engaging said lever, said rod being guided in a substantially Vertical direction in a hole or" said horizontal wall; a recess forming the upper end of said rod in said upper chamber and accommodating said movable Contact member so that it is lifted from said stationary contact members when said rod reaches substantially the upper end position under the action oi' said eccentric and said lever; and a compression spring arranged in said recess and urging said movable Contact member against said stationary contactl members, whereby the stroke oi said compression spring is constant during the opening ci said Contact members.

l2. A contact arrangement for mechanical current converters, comprising in combination, a frame having a substantially horizontal wall and an upper and a lower chamber arranged, respectively, above and below said horizontal wall; two stationary contact members arranged in said upper chamber; a movable contact member arranged in said upper chamber and adapted to bridge in one end position thereof said stationary contact members; a first shaft penee trating into said lower chamber and driven syn chronously With the current to be converted; an eccentric arranged on said first shait in said lower chamber; a pivoted lever arranged in said lower chamber and engaging said eccentric; a substantially vertical pin arranged in an aperture of said horizontal wall and forming at 'the lower end thereof the pivot of said lever; a second shaft adapted for angular adjustment; an arm rigidly secured to said second shaft and connected to said pin so as to adjust it with respect to said horizontal wall; screw means connected to said pin and adapted to adjust said pin with respect to said horizontal wall; a substantially vertical rod having a lower end arranged in said lower chamber and engaging said lever, said rod being guided in a substantially vertical direction in a hole of said horizontal wall; a recess forniing the upper end of said rod in said upper chamber and accommodating said movable contact member so that it is lifted from said stationary contact members when said rod reaches substantially the upper end position under the action of said eccentric and said lever; a conipression spring arranged in said -recess and urging said movable contact member against said stationary contact members, whereby the stroke of said compression spring is constant durn ing the opening of said contact members; and a leaf spring connecting said recess forming the upper end of said rod to said frame.

13. A contact arrangement for current converters, comprising in combination, a frame having a substantially horizontal wall and an upper and a lower chamber arranged,

respectively, above and below said horizontal wall; two stationary contact members arranged. in said upper chamber; a movable contact member arranged in said upper chamber and adapted to bridge in one end position thereof said stationary contact members; a rst shaft penetrating into said lower chamber and driven synchronously with the current to be converted; an eccentric arranged on said first shaft in said lower chamber; a pivoted lever arranged in said lower chamber and engaging said eccentric; a substantially vertical pin arranged in an aperture of said horizontal wall and forming at the lower end thereof the pivot of said lever; a second shaft adapted for angular adjustment; an arm rigidly secured to said second shaft and connected to said pin so as to adjust it with respect to said horizontal wall; screw means connected to said pin and adapted to adjust said pin with res ect to said horizontal wall; a substantially vertical rod having a lower end arranged in said lower chamber and engaging said lever, said rod being guided in a substantially vertical direction in a hole of said horizontal wall; a recess forming the 'upper end of said rod in said upper chamber and accommodating said movable contact member so that it is lifted from said stationary contact members when said rod reaches substantially the upper end position under the action of said eccentric and said lever; a compression spring arranged in said recess and urging said movable contact member against said stationary contact members, whereby the stroke of said compression spring is constant during the opening of said contact members; and a compression spring arranged between the upper end of said rod and said frame.

14. A contact arrangement for mechanical current converters, comprising in combination, a frame having a substantially horizontal wall and an upper and a lower chamber arranged, respectively, above and below said horizontal wall; two stationary contact members arranged in said upper chamber; a movable contact member arranged in said upper chamber and adapted to bridge in one end position thereof said stationary contact members; a iirst shaft penetrating into said lower chamber and driven synchronously with the current to be converted; an eccentric arranged onV said first shaft in said lower chamber; a pivoted lever arranged in said lower chamber and engaging said eccentric; a substantially vertical pin arranged in an aperture of said horizontal wall and forming at the lower end thereof the pivot of said lever; a second shaft adapted for angular adjustment; an arm rigidly secured to said second shaft and connected to said pin so as to adjust it with respect to said horizontal wall; screw means connected to said pin and adapted to adjust said pin with respect to said horizontal wall; a substantially vertical rod having a lower end arranged in said lower chamber and engaging said lever, said rod being guided in a substantially vertical direction in a hole of said horizontal wall; a recess forming the upper end of said rod in said upper chamber and accommodating said movable Contact member so that it is lifted from said stationary contact members when said rod reaches substantially the upper end position under the action of said eccentric and said lever;

a compression spring arranged in said recess and urging said movable contact member against said stationary contact members, whereby the stroke of said compression spring is constant 1 during the opening of said Contact members;

a leaf spring connecting said recess forming the upper end of said rod to said frame; and a compression spring arranged between the upper end of said rod and said frame.

15. A contact arrangement for mechanical current converters, comprising, in combination, an eccentric adapted to be driven synchronous with the current to be converted; a movable member engaging said eccentric and synchronously moving with the same; a rod having one end thereof connected with said movable member so as to move synchronous with said eccentric, said rod having a recessed portion at the other end thereof; spring means urging said rod in one direction toward said eccentric; a compression spring located in said recessed portion and having one end secured to the other end of said rod and moving with the same; a movable contact member located in said recessed portion and being secured to the other end of said compression spring and urged by the same to move in said one direction to an end position abutting against said recessed portion; and a stationary contact located adjacent said recessed portion and being engaged and closed by said movable contact during movement of said rod in said one direction toward said eccentric.

16. A contact arrangement for mechanical current converters, comprising, in combination, an eccentric adapted to be driven synchronous with the current to be converted; a movable recessed member engaging said eccentric and synchrom nously moving with the same; a rod having one end thereof secured to said movable member so as to move synchronous with said eccentric in a small rotational movement, said rod having a recessed portion at the other end thereof; leaf spring means engaging the other end of said rod and urging said rod in one direction toward said eccentric; a compression spring located in said recessed portion and having one end secured to the other end of said rod and moving with the same; a movable contact member located in said recessed portion and being secured to the other end of said compression spring and urged by the same to move in said one direction to an end position abutting against said recessed portion; and a stationary contact locatedA adjacent said recessed portion and being engaged and closed by said movable contact during movement of said rod in said one direction toward said eccentric.

FLORIS KOPPELMANN.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 731,375 Liggett June 16, 1903 1,286,795 Sandell Dec. 3, 1918 1,807,376 Braden May 26., 192i 2,128,427 Means Aug. 30, 1938 2,276,698 Pierce Mar. 17, 1942 2,289,086 Van Valkenburg July 7, 1942 2,353,427 Zellweger July 11, 1944 2,375,416 Huber May 8, 1945 2,439,747 Nelson Apr. 13, 1948 

